The primary objective is to compare risk factors for the less common histologic types of breast cancer, such as lobular and medullary cancers with the more common infiltrating ductal types which comprise approximately 80% of breast cancers in the United States. Preliminary epidemiologic data is suggesting that the less common types of breast cancer may have some epidemiologic characteristics of their own. Although lobular and medullary breast cancers are relatively rate, it is conceivable they may fit into epidemiologically definable patterns.